package com.cheng.dreams.sample.util;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;

/**
 * Created by Kai on 2015/8/25.
 */
public class DividerGridItemDecoration extends RecyclerView.ItemDecoration
{

private static final int[] ATTRS = new int[] { android.R.attr.listDivider };
private Drawable mDivider;

public DividerGridItemDecoration(Context context)
        {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        }

@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state)
        {

        drawHorizontal(c, parent);
        drawVertical(c, parent);

        }

private int getSpanCount(RecyclerView parent)
        {
        // 列数
        int spanCount = -1;
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager)
        {

        spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
        } else if (layoutManager instanceof StaggeredGridLayoutManager)
        {
        spanCount = ((StaggeredGridLayoutManager) layoutManager)
        .getSpanCount();
        }
        return spanCount;
        }

public void drawHorizontal(Canvas c, RecyclerView parent)
        {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++)
        {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
        .getLayoutParams();
final int left = child.getLeft() - params.leftMargin;
final int right = child.getRight() + params.rightMargin
        + mDivider.getIntrinsicWidth();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
        }
        }

public void drawVertical(Canvas c, RecyclerView parent)
        {
final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++)
        {
final View child = parent.getChildAt(i);

final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
        .getLayoutParams();
final int top = child.getTop() - params.topMargin;
final int bottom = child.getBottom() + params.bottomMargin;
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicWidth();

        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
        }
        }

private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
                            int childCount)
        {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager)
        {
        if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
        {
        return true;
        }
        } else if (layoutManager instanceof StaggeredGridLayoutManager)
        {
        int orientation = ((StaggeredGridLayoutManager) layoutManager)
        .getOrientation();
        if (orientation == StaggeredGridLayoutManager.VERTICAL)
        {
        if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
        {
        return true;
        }
        } else
        {
        childCount = childCount - childCount % spanCount;
        if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
        return true;
        }
        }
        return false;
        }

private boolean isLastRaw(RecyclerView parent, int pos, int spanCount,
                          int childCount)
        {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager)
        {
        childCount = childCount - childCount % spanCount;
        if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
        return true;
        } else if (layoutManager instanceof StaggeredGridLayoutManager)
        {
        int orientation = ((StaggeredGridLayoutManager) layoutManager)
        .getOrientation();
        // StaggeredGridLayoutManager 且纵向滚动
        if (orientation == StaggeredGridLayoutManager.VERTICAL)
        {
        childCount = childCount - childCount % spanCount;
        // 如果是最后一行，则不需要绘制底部
        if (pos >= childCount)
        return true;
        } else
        // StaggeredGridLayoutManager 且横向滚动
        {
        // 如果是最后一行，则不需要绘制底部
        if ((pos + 1) % spanCount == 0)
        {
        return true;
        }
        }
        }
        return false;
        }

@Override
public void getItemOffsets(Rect outRect, int itemPosition,
                           RecyclerView parent)
        {
        int spanCount = getSpanCount(parent);
        int childCount = parent.getAdapter().getItemCount();
        if (isLastRaw(parent, itemPosition, spanCount, childCount))// 如果是最后一行，则不需要绘制底部
        {
        outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else if (isLastColum(parent, itemPosition, spanCount, childCount))// 如果是最后一列，则不需要绘制右边
        {
        outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else
        {
        outRect.set(0, 0, mDivider.getIntrinsicWidth(),
        mDivider.getIntrinsicHeight());
        }
        }
        }
